<!DOCTYPE html>
<html lang="zh-CN">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>页面未找到</title>
    <style>
        body {
            font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
            background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
            min-height: 100vh;
            display: flex;
            align-items: center;
            justify-content: center;
            margin: 0;
            padding: 20px;
        }
        
        .container {
            background: white;
            border-radius: 20px;
            padding: 40px;
            text-align: center;
            box-shadow: 0 20px 40px rgba(0, 0, 0, 0.1);
        }
        
        h1 {
            color: #333;
            font-size: 48px;
            margin-bottom: 20px;
        }
        
        p {
            color: #666;
            font-size: 18px;
        }
    </style>
</head>
<body>
    <div class="container">
        <h1>404</h1>
        <p>页面未找到</p>
        <p>请访问 /callback 或 /fallback 进行授权回调</p>
    </div>
</body>
</html>